When you deploy an application, you must also deploy the files that are required to support it. If any of these files are provided by Microsoft, check whether you are permitted to redistribute them. To review the Microsoft Software License Terms, see License.htm in the directory where Visual Studio is installed, or on the Visual Studio installation media. To view the "REDIST list" that is referenced in the "Distributable Code" section of the Microsoft Software License Terms for certain editions of Visual Studio, see Distributable Code for Microsoft Visual Studio 2015 and Microsoft Visual Studio 2015 SDK on the Microsoft website. For more information about redistributable files, see Determining Which DLLs to Redistribute and Deployment Examples.

To deploy redistributable Visual C++ files, you can use the Visual C++ Redistributable Packages (VCRedist_x86.exe, VCRedist_x64.exe, or VCRedist_arm.exe) that are included in Visual Studio. These files can be found under your Visual Studio installation directory in Program Files [(x86)]\Microsoft Visual Studio version\VC\redist\locale\. Another option is to use redistributable merge modules (.msm files), which can be found in Program Files [(x86)]\Common Files\Merge Modules\. It's also possible to directly install redistributable Visual C++ DLLs in the application local folder, which is the folder that contains your executable application file. For servicing reasons, we do not recommend that you use this installation location.

The Visual C++ Redistributable Packages install and register all Visual C++ libraries. If you use one, you must set it to run on the target system as a prerequisite to the installation of your application. We recommend that you use these packages for your deployments because they enable automatic updating of the Visual C++ libraries. For an example about how to use these packages, see Walkthrough: Deploying a Visual C++ Application By Using the Visual C++ Redistributable Package.

Each Visual C++ Redistributable Package checks for the existence of a more recent version on the machine. If a more recent version is found, the package is not installed. Starting in Visual Studio 2015, redistributable packages display an error message stating that setup failed. If a package is run by using the /quiet flag, no error message is displayed. In either case, an error is logged by the Microsoft installer, and an error result is returned to the caller. Starting in Visual Studio 2015 packages, you can avoid this error by checking the registry to find out if a more recent version is installed. The currently installed version is stored in the HKEY_LOCAL_MACHINE\SOFTWARE[\Wow6432Node]\Microsoft\VisualStudio\vs-version\VC\Runtimes\{x86|x64|ARM} key, where vs-version is the version number for Visual Studio (14.0 for Visual Studio 2015), and where the key is ARM, x86, or x64 depending on the installed vcredist versions for the platform. (You don't need to check under the Wow6432Node subkey unless you are using RegEdit to view the version of the installed x86 package on an x64 platform.) The version number is stored in the REG_SZ string value Version and also in the set of Major, Minor, Bld, and Rbld REG_DWORD values. To avoid an error at install time, you must skip installation of the redistributable package if the currently installed version is a more recent version.

If a Visual C++ library DLL is not reachable and Windows cannot load it for your application, this message may be displayed: This application has failed to start because MSVCR<version number>.dll was not found. Re-installing the application may fix this problem.